Kbase 11330: Support for pre-V7 code running on Version 7/8 and higher
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/05/1998 |
|
Support for pre-V7 code running on Version 7/8 and higher
When using pre-V7 4GL code with V7 or later, programmers will find
that compatibility is provided mainly in TTY (character) mode. Even in
TTY mode, however, there will be some limitations. For instance, PUT
SCREEN and PUT CURSOR cannot be completely supported in V7+ on any
platform. This is due to emulation software that has been integrated
into PROGRESS in order to provide cross-platform support for the event
driven constructs now supported in the GUI versions of V7 and higher.
The consequence of this integration has been that the core PROGRESS
product can no longer claim complete "control" of the placement of
objects on the frame using commands such as PUT. In addition, objects
such as variables and frames take on widget-like properties that
include borders.
The problems of porting pre-V7 code to the GUI (_prowin) versions of
V7 and higher are even greater, due to the many environmental issues
imposed by Windows.
These are some of the limitations alluded to in the Preface of the
Migration Guide for Version 8.2A, on p. ix: "This guide does not
address issues involved in migrating Version 6 code to a Version 8
graphical user interface (GUI) platform. If you wish to migrate to
Version 8 on a GUI platform, you should anticipate making extensive
changes to accommodate native user interface behaviors."
For example, a variable of format "X(80)" by default will take on
the characteristics of a FILL-IN widget and take up more screen space
than 80 characters. In GUI, you may have to change it to display a
text widget. There is no way to circumvent this other than to modify
source code or to choose to run in the more compatible TTY executable
(_progres).
Generally speaking, there is a good chance that V6 code will have to
be modified to run in GUI mode on Version 7 and later. Progress is
committed to providing as trouble-free a migration path as possible on
the CHARACTER versions of V7 and higher, where the impact of Windows
is minimized or eliminated. This commitment cannot be offered on the
GUI versions of V7+ due to factors imposed by the native windowing
environment, which PROGRESS cannot control.
For additional information, please see Kbase 11783, "4GL concerns
when moving from V6 PROGRESS to V7 or V8".
Progress Software Technical Support Note # 11330